The invention relates to a method for sequence programming of an injection molding cycle of an injection molding machine.
It is known in the art to program an injection molding cycle, i.e., the operation of an injection molding machine, with a user-definable controller (SPS) located on the injection molding machine itself (online) or remote from the injection molding machine at a separate terminal (off-line). During online programming, the injection molding machine is not available for the production for a considerable length of time. Conversely, during off-line programming, the injection molding machine typically needs to be stopped only for a short time to make final fine-adjustments in the program.
Such user-definable controllers typically include data processing program for setup and operation of an injection molding machine. Each manufacturer of an injection molding machine typically offers a user-definable control customized for the (proprietary) machine program. However, in these controllers the process flow of an injection molding cycle cannot be changed or only with the help of the machine manufacturer. The user or processor cannot program the controller.
Modifications are user-definable sequence controllers, wherein the user or processor is provided in the controller with tools which can be configured to assemble the process flow of an injection molding cycle from predefined elements (macros). Such stored program process controllers are described in the publication “Kunststoffe” (Plastics), Vol. 08/2003, pages 46-49.
The processor using injection molding machines from different manufacturers must have experience with different user-definable sequence controllers in order to be able to correctly program all process flows and movements required for the manufacture of a certain product.
Already a user-definable sequence controllers from a single manufacturer is not easy to master; and if a person is not constantly involved with the program and if a new process needs to be programmed only after a considerable time (for example, because a different product is to be manufactured), then the person must first familiarize himself with this program, which is quite time-consuming. The situation becomes more difficult, when injection molding machines from different manufacturers must be programmed and hence different user-definable sequence controllers must be mastered.
Flow diagrams supplied by mold manufacturers help somewhat when programming a process flow of an injection molding machine. Such flow diagrams described and illustrated in detail when which part of a mold needs to perform which type of movement, so that at the end the molded part is correctly produced and can be flawlessly removed from the mold. However, these flow diagrams must still be entered into the user-definable sequence controller (SPS) or converted to the “correct” program sequence, which requires a certain knowledge concerning these controllers. Moreover, such flow diagrams are not available for each mold. In addition, errors may occur when information about positions, such as “advanced” and “retracted”, or “moved in” and “move out” are not unambiguous. It has to be taken into account that the operating personnel frequently does not have technical knowledge about injection molding machine and molds.
The fundamental problem with all user-definable controllers (SPS) and the aforedescribed user-definable sequence controllers is that the entire injection molding cycle is initially entered in the controller and thereafter executed in its entirety, without being able to risk-free test the cycle or sections of the cycle. Errors have the potential to severely damage the molds.
To simplify programming of machines, so-called “teach-in systems” are known. These are auxiliary tools designed to facilitate programming of complex machines which typically do not require programming experience or knowledge about the machine control. DE 199 00 117 A1 discloses a teach-in system for programming grinding machines or other machine tools. This teach-in system includes a graphic user interface for visualization of blanks, workpieces and tools. The illustrated elements can be placed in any relation with one another by moving corresponding control elements. The resulting movements are recorded by the teach-in module and translated into a machine control program; alternatively, an existing machine control program is altered by the movements. This system represents a so-called virtual teach-in system.
Other teach-in methods and teach-in systems are known from programmable industrial robots, for example to teach the controller of the robot the movement of a manipulator arm relative to a workpiece (teaching the robot). The desired movement of the robot is manually entered into an input device, either numerically or graphically. A data processing program converts these input values into a “movement program” for the industrial robot, i.e., the motion sequence is programmed automatically. Teach-in systems for industrial robots are disclosed, for example, in EP 0 792 726 B1 and U.S. Pat. No. 4,224,501. EP 1 048 995 A2 also discloses a virtual teach-in system for a robot for removing injection-molded parts from the mold of an injection molding machine.
U.S. Pat. No. 4,696,632 discloses a teach-in method for an injection molding machine, wherein a movable mold half is moved from a closed position to an open position; positions are taught where the movable mold half is accelerated or decelerated depending on the direction of travel, so that the desired end position is reached correctly.